GDDS-V1.2

An Open Source

NSS

ata

ownload

oftware

User Manual

Sat April 10 12:38:06 UTC 2024

GDDS User Manual

Contents

1 Before You Start ....................................................................................................... 1

1.1 End-User License Agreement .......................................................................................... 1

1.2 Scope of Operation .......................................................................................................... 1

1.3 Update Description .......................................................................................................... 2

1.4 Contact Us ....................................................................................................................... 2

1.5 Bug Reports/Comments................................................................................................... 2

1.6 Version History ............................................................................................................... 2

2 Software Instructions................................................................................................ 3

2.1 Software Acquisition ....................................................................................................... 3

2.2 Software Installation ........................................................................................................ 3

2.3 Module Introduction ........................................................................................................ 4

3 Operation Module ..................................................................................................... 5

3.1 “Global IGS data” Module .............................................................................................. 5

3.1.1 File Type ................................................................................................................... 6

3.1.2 Time Range .............................................................................................................. 6

3.1.3 IGS Station ............................................................................................................... 6

3.1.4 Data Center ............................................................................................................... 8

3.1.5 Output Path ............................................................................................................... 8

3.1.6 Function Button ........................................................................................................ 8

3.2 “Post-Processing Product” Module ................................................................................. 8

3.2.1 Institution .................................................................................................................. 9

3.2.2 Product Type .......................................................................................................... 10

3.2.3 Time Range ............................................................................................................ 10

3.2.4 Output Path ............................................................................................................. 11

3.2.5 Function Button ...................................................................................................... 11

3.3 “Regional CORS Data” Module .................................................................................... 11

3.3.1 CORS Source.......................................................................................................... 12

3.3.2 File Type ................................................................................................................. 12

3.3.3 Time Range ............................................................................................................ 12

3.3.4 CORS Station ......................................................................................................... 12

3.3.5 Output Path ............................................................................................................. 14

3.3.6 Function Button ...................................................................................................... 14

3.4 “Time Series Product” Module ..................................................................................... 14

3.4.1 Institution ................................................................................................................ 15

3.4.2 File Type ................................................................................................................. 15

GDDS User Manual

3.4.3 Time Range ............................................................................................................ 16

3.4.4 Station ..................................................................................................................... 16

3.4.5 Output Path ............................................................................................................. 16

3.4.6 Function Button ...................................................................................................... 16

3.5 “Custom Download” Module ........................................................................................ 16

3.5.1 URL Templates ...................................................................................................... 17

3.5.2 Setting Protocol ...................................................................................................... 17

3.5.3 Setting Domain Name ............................................................................................ 17

3.5.4 Setting File Directory ............................................................................................. 17

3.5.5 Setting File Name ................................................................................................... 17

3.5.6 Output Path ............................................................................................................. 18

3.5.7 Time Span and Site ................................................................................................. 18

3.5.8 Function Button ...................................................................................................... 18

3.6 “Data Decompression” Module ..................................................................................... 18

GDDS User Manual

1 Before You Start

1.1 End-User License Agreement

● GDDS (GNSS Data Download Software) can be used under the following license

conditions:

1. With this license, the copyright holder ECUT permits to use the software GDDS

free of charge in executable form and for non-commercial purposes only.

2. Unless expressly stated in this license, you may not copy, modify, sublicense,

distribute or create any derivate works of the software. Any attempt to copy, modify,

sublicense, or distribute the program in other ways is void and will automatically

terminate your rights under this license.

3. The software is provided “as is” without any express or implied guarantees,

including but not limited to the implied warranties of merchantability and fitness

for some particular purpose. All risks as to the quality and performance of the

program are with you. Should the program prove defective, you assume the cost of

all necessary maintenance, repair, or correction.

4. Under no circumstances, unless required by applicable law or written consent, the

special, incidental, or consequential damages (including but not limited to data

inaccuracies or losses due to third parties, or failures to operate with any other

procedures), even if the holder has been informed of the possibility of such

damages.

5. This clause shall be governed, interpreted, and enforced by the laws of the People’s

Republic of China.

1.2 Scope of Operation

The GDDS is software for GNSS data download, which provides an interactive

interface for the Windows or Linux operating system. The following GNSS data types

are supported to download:

● Observation data

● Navigation data

● Meteorology data

● Post-processing product (i.e., precise ephemeris, precise clock, troposphere, global

ionosphere maps, ionospheric spherical harmonic model, rate of TEC index,

antenna phase center model, earth rotation parameters, satellite attitude

information, satellite yaw information, differential code bias, bias-SINEX, and

daily/weekly solution)

● Time series products

The following operations/tasks are supported:

GDDS User Manual

● Time transformation

● Map-based IGS/CORS station selection

● Station information inquiry

● IGS/CORS station display

● Data download customization

● Data decompression

1.3 Update Description

This update introduces GDDS v1.2 which is mainly changed from the previous GDDS

v1.1 in the "Post Processing Product" download module. It supports a new product

naming method and can download corresponding data.

1.4 Contact Us

There is an e-mail address lglu66@163.com for information transfer (new features,

versions, etc.) or prompt answer not included in the documentation.

1.5 Bug Reports/Comments

For bug reports or comments, please contact the email address lglu66@163.com.

Please follow the procedure below for bug reports:

● Make sure to use the latest version.

● If you are using the latest version, please provide complete download information

settings.

● Try to offer a detailed description of the problem generation process. If possible,

please attach a screenshot of the GDDS interface to your e-mail.

1.6 Version History

2024-4-10 (V1.2)

●

The software has updated URL addresses for some products and data that are

invalid

●

The software has added a time series product download module

GDDS User Manual

2 Software Instructions

2.1 Software Acquisition

Any group or individual can contact the email address

lglu66@163.com

to apply for

the latest version of GDDS free of charge. Please indicate the applicant's information

and software purpose in the email.

2.2 Software Installation

After downloading and opening the “GDDS.zip” software package, users can obtain

the “Windows.zip” and “Linux.zip” version compressed files in the bin folder, which

contains the running environment and executable program of the software. After

decompressing the required version file, users can find the executable program

“GDDS.exe” and double-click it to run without installation. It is recommended to close

the anti-virus software to avoid deleting the executable file by mistake.

Fig. 2.1

Example of executable file storted in “\GDDS\bin\Windows\GDDS.exe”

After double-clicking “GDDS.exe”, the software will start to run. The main interface

of the software is shown in Fig. 2.2.

Fig. 2.2

Software main interface

GDDS User Manual

2.3 Module Introduction

GDDS consists of five modules, i.e., Global IGS data, Post-processing product,

Regional CORS data, Custom download, and Data decompression. Among them, the

first three modules are used to download various GNSS data and products shown in

Table 1. “Custom Download” module can execute the download link of user-defined

configuration. The last module supports batch decompression of UNIX compressed

files (with Z, gz as extensions) and CRINEX files (with d, crx as extensions).

Table 1

Download content corresponding to different modules of GDDS

Module

Download source

File type

Global IGS data

1.WHU (China)

2.IGN (France)

3.ESA (Europe)

4.KASI (Korea)

5.SIO (USA)

6.CDDIS (USA)

1.RINEX 2.11/3.xx observation data (o/mo)

2.RINEX 2.11/3.xx meteorology data (m/mm)

3.RINEX 2.xx/3.xx navigation data (n/mn)

Post-processing product

1.IGS

2.JPL (USA)

3.MIT (USA)

4.ESA (Europe)

5.GRG (France)

6.CAS (China)

7.UPC (Spain)

8.CODE

(Switzerland)

9.SIO (USA)

10.NGS (USA)

11.EMR (Canada)

12.GFZ (Germany)

13.WHU (China)

1.Precise ephemeris (sp3/eph)

2.Precise clock (clk)

3.Satellite yaw information (yaw)

4.Earth rotation parameters (erp)

5.Satellite attitude information (obx)

6.Antenna phase center model (atx)

7.Troposphere (tro/zpd)

8.Ionospheric-spherical harmonic model (ion)

9.Global ionosphere maps (i)

10.Rate of TEC index (f)

11.Differential code bias (dcb)

12.OSB Bias-SINEX (bia)

13.REL Bias-SINEX (bia)

14.DCB Bias-SINEX (bsx)

15.Daily/Weekly solution (snx)

Regional CORS data

1.USA CORS

2.Europe EPN

3.Spain CORS

4.Japan JPN

5.HongKong CORS

1.RINEX 2.11/3.xx observation data (o/mo)

2.RINEX 2.11/3.xx meteorology data (m/mm)

3.RINEX 2.xx/3.xx navigation data (n/mn)

4.Partial products

GDDS User Manual

6.Curtin University

7.Australia APREF

Time series product

1.EQDSC (China)

2.NGL (USA)

3.SOPAC (USA)

4.UNAVCO (USA)

5.IERS (Global)

1.Combine time series (tar)

2.Time series (txt)

3.Residue time series (dat)

4.IGS14_XYX (txyz2)

5.IGS14_NEU (tenv3)

3 Operation Module

3.1 “Global IGS data” Module

The “Global IGS data” module mainly downloads GNSS data provided by the IGS data

centers. You can click the “Global IGS data” button in the GDDS main interface to run

this module. The “Global IGS data” operation interface is shown in Fig. 3.1.

Fig. 3.1

“Global IGS data” operation interface

GDDS User Manual

3.1.1 File Type

The file types supported in this module are mainly observation data, navigation data,

and meteorology data of RINEX version 2.11 and 3. xx provided by the IGS data center.

You can choose to download one or more file types as needed. Since observation data

and meteorology data are related to IGS stations, the corresponding IGS station needs

to be added in the subsequent process when this file type is selected.

3.1.2 Time Range

Then set the start and end time corresponding to the download file. You can select one

of any three different modes to express time, such as Year-Month-Day (Year-Month-

Day Hour-Minute, Year-Month-Day Hour), Year with DOY, GPS week with Day of

week. The software will automatically switch to the other two according to the input

mode, which is convenient for users. It should be noted that the data released by IGS

has a certain lag, so when setting the start and end time, you can move forward slightly

at the current time.

3.1.3 IGS Station

When the observation data or meteorology data is selected in the file type, it is also

necessary to choose and add the corresponding IGS station. The interface of the IGS

station is illustrated in Fig. 3.2 below.

Fig. 3.2

IGS station interface

On the left is the text box for searching and selecting the target IGS station.

Stations displayed in this session will be updated in real-time according to the file type

in order to ensure effectiveness and correctness. If you have specific requirements for

the IGS station name, you can search for the station name based on this part and select

the corresponding station name.

The text box on the right is a collection of the selected station information. The

corresponding station for the final data download should be subject to the one shown in

this part. You can add, modify and delete station information in here.

In the middle are some function buttons. The “Map Choose” button can open the

map interaction function, which not only displays the global distribution of IGS stations

but also supports a variety of interactive functions, such as single station selection,

frame selection (i.e., rectangle, polygon, and circle), distance measurement, area

calculation, etc. IGS map interactive function is exhibited in Fig. 3.3.

The “Info Inquire” button will generate the station information table, which is used

GDDS User Manual

to query some basic information of the IGS station, such as coordinates (longitude and

latitude), receiver type, antenna type, etc, and support the operation of modifying,

adding, deleting, exporting, saving and restoring the content of the station information

table. IGS information retrieval function is displayed in Fig. 3.4.

The “Add Station” button can add the selected station on the left to the text box on

the right. The “Map Display” button displays the selected stations in the right-hand text

box on the map. The “Clear Station” is to quickly clear all stations in the text box on

the right.

Fig. 3.3

IGS map interactive function interface

Fig. 3.4

IGS information retrieval function interface

GDDS User Manual

3.1.4 Data Center

The download sources supported by this module are six global data centers of IGS,

namely WHU in China, IGN in France, ESA in Europe, CDDIS in the United States,

SIO in the United States, and KASI in Korea. Users from different countries can choose

the appropriate data center here to achieve the best download speed.

3.1.5 Output Path

Finally, select the output path of the download file. The default output path is the

“Download “ folder on the computer desktop. You can also set other output paths as

needed. Note that if the output path does not exist in the computer, the software will

automatically create a corresponding folder according to the input path.

3.1.6 Function Button

There is a row of function buttons at the bottom of the module, namely “Download”,

“Detail”, “Open” and “Help”. The “Download” button is used to start the download

task. The “detail” button aims to open the log file of the entire download task, which

also contains the analysis of the failure download task. The “Open” button can be

devoted to conveniently the download folder open. The “Help” button is to quickly

open the “GDDS User Manual” file.

3.2 “Post-Processing Product” Module

The “Post-Processing Product” module mainly downloads GNSS products provided by

the IGS analysis center and other relevant data computation institutions. You can click

the “Post-Processing Product” button in the GDDS main interface to run the module.

The interface of this module is shown in Fig. 3.5.

Fig. 3.5

“Post-Processing Product” operation interface

GDDS User Manual

3.2.1 Institution

Different institutions have their own post-processing products, which can be found on

their own websites as well as on the websites of other institutions for data sharing

reasons. Therefore, in the post-processing product module, users can choose different

websites to download products. The URLs supported by different institutions are shown

in Table 2.

Table 2

Available URLs for products provided by different institutions

Institution

URL

IGS

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

http://garner.ucsd.edu

/pub/products/

CODE

http://ftp.aiub.unibe.ch/

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

http://garner.ucsd.edu

/pub/products/

CAS

ftp://182.92.166.182/product/

ftp://ftp.gipp.org.cn/product/

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

WHU

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://igs.gnsswhu.cn/pub/whu/

ftp://gssc.esa.int/gnss/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

GFZ

ftp://ftp.gfz-potsdam.de/GNSS/products/

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gnss/products/

http://garner.ucsd.edu

/pub/products/

ESA

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

http://garner.ucsd.edu

/pub/products/

JPL

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

GDDS User Manual

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

http://garner.ucsd.edu

/pub/products/

MIT

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

http://garner.ucsd.edu

/pub/products/

GRG

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

EMR

ftp://rtopsdata1.geod.nrcan.gc.ca/gps/products/

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/'

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp:

//nfs.kasi.re.kr/gps/products/

SIO

http://garner.ucsd.edu/pub/products/

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

NGS

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

ftp://igs.ensg.ign.fr/pub/igs/products/

ftp://nfs.kasi.re.kr/gps/products/

UPC

ftp://gssc.esa.int/gnss/products/

ftp://igs.gnsswhu.cn/pub/gps/products/

ftp://gdc.cddis.eosdis.nasa.gov/pub/gps/products/

3.2.2 Product Type

The product types supported by this module include precise ephemeris (.sp3/.eph),

precise clock (.clk), satellite yaw information (.yaw), earth rotation parameters (.erp),

satellite attitude information (.obx), antenna phase center model (.atx), troposphere

(.tro/.zpd), ionospheric spherical harmonic model (.ion), global ionosphere maps (.i),

rate of TEC index (.f), differential code bias (.dcb), bias-SINEX (.bia), and daily/weekly

solution (.snx). There are differences in the types of products provided by different

institutions (Tips: G/R is GPS/GLONASS, MGEX is multi-GNSS, and unstatement is

GPS/GLONASS).

3.2.3 Time Range

Similarly, set the start and end time corresponding to the download file. As mentioned

above, you can select any one of the three modes to express time, and then the software

GDDS User Manual

will automatically realize time conversion. Please note that those products provided by

institutions have a certain lag, so it is suggested to move forward slightly at the current

time when setting the start and end times.

3.2.4 Output Path

Choose the output path of the download files. The default output path is the “Download”

folder on the computer desktop. You can also set another output path as required. When

the output path does not exist in the computer, the software will automatically create

the corresponding folder according to the input path.

3.2.5 Function Button

There is a row of function buttons below this module, namely “Download”, “Detail”,

“Open”, and “Help”. Each function is similar to the previous section.

3.3 “Regional CORS Data” Module

The “Regional CORS Data” module mainly downloads GNSS data and partial products

provided by CORS. You can click the “Regional CORS Data” button in the GDDS main

interface to run this module. The interface of this module is shown in Fig. 3.6.

Fig. 3.6

“Regional CORS Data” operation interface

GDDS User Manual

3.3.1 CORS Source

The download sources supported by this module are CORS, namely American CORS,

Australian APREF, European EPN, Spanish CORS, Hong Kong CORS, and Curtin

University. You can select data and products from different CORS to download

according to your needs.

3.3.2 File Type

The file types supported by this module include observation data, navigation data,

meteorology data, and some products (such as precise ephemeris, precise clock, small

cycle slip, and weekly solution). Different CORS provides different file types.

3.3.3 Time Range

As is stated above, you can set the start and end time in any of three ways, and then the

software automatically realizes time transformation. It should be noted that those data

provided by CORS have a certain lag, so when setting the start and end time, please

move forward slightly at the current time.

3.3.4 CORS Station

When selecting the observation or meteorology data, you also need to choose and add

the corresponding CORS station. The interface design of the CORS station is divided

into three parts, as shown in Fig. 3.7.

Fig. 3.7

CORS station interface display

On the left is the text box for searching and selecting the target CORS station.

Stations displayed here will be updated in real-time based on the selected file type and

the CORS source. When you have specific requirements for CORS station name, you

can search for the station name and then select the corresponding station.

The text box on the right is a summary of the added CORS station information.

The corresponding station for the final data download should be according to the one

shown in this part, and it can also be added, modified, and deleted in here.

GDDS User Manual

Fig. 3.8

American CORS map interactive function interface

In the middle are some function buttons. The “Map Choose” button can implement

the map interaction function, which not only shows the global distribution of CORS

stations but also supports various interactive functions, such as single station selection,

frame selection (namely rectangle, polygon, circle), distance measurement, area

calculation, etc. Take the American CORS map interactive function as an example, as

exhibited in Fig. 3.8.

The “Info Inquire” button can create the station information table to query some

basic information of the CORS station, such as the station coordinates (longitude and

latitude), receiver type, and antenna type, and support the operation of modifying,

adding, deleting, exporting, saving and restoring the content of the station information

table. Take the American CORS information retrieval function as an example, and the

software interface is displayed in Fig. 3.9.

GDDS User Manual

Fig. 3.9

American CORS information retrieval function interface

The “Add Station” button adds the selected station on the left to the text box on

the right. The “Map Display” button intuitively displays CORS stations in the right-

hand text box on the map. The “Clear Station” is to quickly clear all stations in the text

box on the right.

3.3.5 Output Path

As commented earlier, you can use the default output path on the computer desktop or

set another appropriate output path.

3.3.6 Function Button

Function buttons at the bottom of this module are the same as described above, not tired

in words here.

3.4 “Time Series Product” Module

The “Time Series Product” module mainly downloads GNSS time series product

provided by some research institutions. You can click the “Time Series Product” button

in the GDDS main interface to run the module. The interface of this module is shown

in Fig. 3.10.

GDDS User Manual

Fig. 3.10

“Time Series Product” operation interface

3.4.1 Institution

The download sources supported by this module are China EQDSC, USA NGL, USA

SOPAC, USA UNAVCO, and IERS. You can select data and products from different

research institutions to download according to your needs. The URLs supported by

different institutions are shown in Table 3.

Table 3

Available URLs for time series products provided by different institutions

Institution

URL

EQDSC

https://www.eqdsc.com/eastern/upload/gnss/kssjxl/ys/

NGL

http://geodesy.unr.edu/gps_timeseries/

http://geodesy.unr.edu/tsplots/

OPAC

ftp://sopac

ftp.ucsd.edu/pub/timeseries/measures/

UNAVCO

https://geodesy.noaa.gov/corsdata/coord/

IERS

https://itrf.ign.fr/ftp/pub/itrf/

3.4.2 File Type

The file types supported by this module include combine time series, time series,

residue time series, IGS14_XYX, and IGS14_NEU. Different research institutions

provide different file types.

GDDS User Manual

3.4.3 Time Range

As is stated above, you can set the start and end time in any of three ways, and then the

software automatically realizes time transformation. It should be noted that those data

provided by research institutions have a certain lag, so when setting the start and end

time, please move forward slightly at the current time.

3.4.4 Station

When downloading time series products, some institution's sources must also add

station information.

3.4.5 Output Path

As commented earlier, you can use the default output path on the computer desktop or

set another appropriate output path.

3.4.6 Function Button

Function buttons at the bottom of this module are the same as described above, not tired

in words here.

3.5 “Custom Download” Module

The “Custom Download” module mainly realizes the download of data according to

the download link configured by the user. You can click the “Custom Download” button

on the main interface of GDDS to start the module. The interface of this module is

shown in Fig. 3.11.

Fig. 3.11

“Custom Download” operation interface

GDDS User Manual

3.5.1 URL Templates

Display the actual details of the self-configured URL in real time, and open the

information setting interface through the “Settings” button to modify, add, delete and

restore it..

3.5.2 Setting Protocol

Select the protocol type corresponding to the target data transmission. There are mainly

three protocol types: ftp, http and https.

3.5.3 Setting Domain Name

Select or add the domain name of the server where the target data is stored.

3.5.4 Setting File Directory

Enter the specific storage path of the target data in the server. When the path contains

variables such as time and station name, you need to refer to the label for input. For

details of the supported labels, see “Label Explanation” at the bottom of the software.

3.5.5 Setting File Name

Enter the file name corresponding to the target data. For the convenience of users, the

file names of most file types are provided in “Common Template”, including RINEX

V3, RINEX V2 and Product. The explains of common template of file name are listed

in Table 4.

Table 4

The explains of common template of file name

File name template Letters

Meaning

<SITE>RNCRC_S_<year4><doy>

HRMN_LEN_FRQ_ST.FMT

RN The number of the receiver;

CRC

A three-digit ISO-3166-1 standard country

code that identifies the site location;

Data source, that is, the data comes from

the receiver (R) or the data stream (S);

HRMN

Observation start time: hour, minute;

LEN The length of the observation period;

FRQ

Sampling interval or sampling frequency

during observation (no such item in

ephemeris file);

Included satellite system and data type, the

first digit indicates the satellite system (M,

G, R, C, E, J, I); the second digit is the data

type, namely observation file (O),

navigation file (N) or Meteorological file

(M);

FMT

There are only two types of extensions:

rnx or crx

;

<site><doy>#.<year2>t #

1 bit, when there are multiple files in a day,

it indicates the number of files in a day.

Usually 0 means all data for a day (one

GDDS User Manual

file);

t type of data;

AAA<week><dow>.TYP

AAA The name of analysis center;

TYP type of solution;

3.5.6 Output Path

Select the output path for the downloaded file. The default output path is the Downloads

folder on your computer desktop. You can also set to other output paths as needed. Tip:

When the folder displayed in the text box does not exist on the computer, the software

will automatically create the folder.

3.5.7 Time Span and Site

Set the time corresponding to the time tag in the download link. You can set three time

formats: year-month-day, year-year cumulative day, GPS week and day of the week,

the software will automatically convert the other two times according to the time you

input, and customize the time in the download link The label is replaced with a specific

time.

Set the specific station corresponding to the station label in the download link. This

action is not required when the configured download link does not contain a station tag.

3.5.8 Function Button

There are some function buttons under the module, namely “Generate URL”,

“Download”, “Open Dir” and “Detail”. “Generate URL” is to generate a specific URL

according to the various information configured in the above steps, and the generated

URL will be loaded and displayed in the left text box; “Download” is to execute the

download task corresponding to the URL in the left text box of the button; “Open Dir”

is to switch the output path of the open file; “Detail” is to view the execution of the task.

3.6 “Data Decompression” Module

The “Data Decompression” module supports the decompression of GNSS data and

products. Based on this module, UNIX compressed files (with Z, gz as extensions) and

CRINEX files (with d, crx as extensions) can be decompressed in batch with “one-

click”.